How to write a sudoku to a .dat file?

Question

Hi guys,

I'm an IT-student in Belgium. For the subject C# we have to make a Sudoku creator, in windowforms. We have to use

a class where needed.

Short description:

We have to arrange that you can create a sudoku of 2X2, 2X3,3X2 and 3X3 dimensions. People can add a number by left

or right mouseclick. The program controls automatically if the sudoku is correct and there's only one solution.

When people click on the Save-button the whole labelarray (= soduku) must be stored in a .dat-file. When the Open-button

is clicked , the program must pickup at random a sudoku out of that file. So all the stored sudokus have to be in an array.

Question

Now is my problem. How can I write a sudoku to a file? And how can I pickup one at random?

I searched a lot, but I haven't find a clear solution.

Hope you guys can help me.

Thanks in advance.

Wim